煤气化细渣的酸-碱协同改性及其CO₂吸附特性与机理

Acid-base synergistic modification of coal gasification fine slag and its CO₂ adsorption performance and mechanism

摘要

为解决煤气化细渣(coal gasification fine slag,CGFS)堆存造成的环境压力与资源浪费问题,通过CGFS的酸-碱协同改性制备出低成本、具有应用潜力的CO₂吸附材料(HKCGFS).采用热重-微分热重(TG-DTG)、傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、N₂吸附-脱附、扫描电子显微镜(SEM)和能量色散X射线光谱(EDS)等多种表征手段系统分析了改性前后材料的物化性质与孔结构演变规律.结果表明:CGFS具有良好的热稳定性,其物相以无定形组分为主,SiO₂为主要特征晶相;酸-碱协同改性显著优化了材料的孔隙结构,HKCGFS的比表面积可达208.95 m²/g,平均孔径约为4.92 nm,呈现出丰富的介孔特征.CO₂吸附性能测试结果显示:HKCGFS 的吸附行为受吸附时间、气体温度及气体压力的协同调控,吸附量随时间延长先增加后趋于平衡,随温度升高而减少,随压力升高而增加;在 25 ℃、100 kPa条件下,60 min内即可达到0.47 mmol/g的平衡吸附量,展现出良好的吸附速率与吸附容量.吸附动力学分析表明,该吸附过程符合伪一级动力学模型,等温吸附行为更符合Freundlich模型,表明HKCGFS对CO₂的吸附以物理吸附为主.

Abstract

To address the environmental pressure and resource waste caused by the storage of coal gasification fine slag(CGFS),the low-cost and promising CO₂ adsorption material(HKCGFS) was prepared by acid-base synergistic modification of CGFS.The physical and chemical properties,as well as the evolution of pore structure of the materials before and after modification,were systematically characterized by thermogravimetry-differential thermogravimetry(TG-DTG),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),N₂ adsorption-desorption,scanning electron microscopy(SEM),and energy dispersive X-ray spectroscopy(EDS).The results showed that CGFS exhibited good thermal stability,with amorphous components as the main phase and SiO₂ as the main characteristic crystalline phase.The acid-base synergistic modification significantly optimized the pore structure of the material.And the specific surface area of HKCGFS could reach 208.95 m²/g,with an average pore diameter of approximately 4.92 nm,showing abundant mesoporous characteristics.The CO₂ adsorption performance tests indicated that the adsorption behavior of HKCGFS was synergistically regulated by adsorption time,gas temperature and gas pressure.The adsorption capacity gradually approached equilibrium with the extension of time,decreased with increasing temperature,but increased with increasing pressure.Under the conditions of 25 ℃ and 100 kPa,the equilibrium adsorption capacity of 0.47 mmol/g could be reached within 60 min,demonstrating the good adsorption rate and adsorption capacity.The adsorption kinetics analysis showed that the adsorption process conformed to the pseudo-first-order kinetic model,and the isothermal adsorption behavior was more consistent with the Freundlich model,revealing that the adsorption of CO₂ by HKCGFS was mainly physical adsorption.

关键词

煤气化细渣 / 酸-碱协同改性 / CO₂吸附 / 机制

Key words

coal gasification fine slag / acid-base synergistic modification / CO₂ adsorption / mechanism

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基金资助

国家自然科学基金(21573171)

陕西省重点研发计划项目(2024GX-YBXM-491)

西安工程大学大学生创新创业训练计划项目(202510709002)